Hard, abrasion resistant coatings are used over a variety of substrates, including, for example, cement, wood, and porous substrates. Particularly demanding substrates to coat include horizontal substrates such as sidewalks, floor tiles, cement garage floors and wood decks. Unfortunately, many of the commercially available coatings in use today for these surfaces suffer from problems such as poor adhesion, or poor water resistance (e.g., “blushing”).
An issue with cement and fiber cement substrates is that they typically require hard, abrasion resistant coatings with excellent adhesion. In the past, this has been addressed with higher-Tg polymer systems. Unfortunately, volatile organic content (VOC) solvents generally must be used to achieve proper coalescence of higher-Tg polymers. Consequently, there is an unmet need to develop acceptable low VOC aqueous based coatings for cement substrates that are hard, blush resistant, abrasion resistant and offer excellent adhesion.
In addition, there is an unmet need for improved fiber cement articles that resist damage from repeated freezing and thawing of water that is absorbed into the substrate. This need is particularly acute in colder climates where freeze-thaw mechanisms can occur. Another problem is that prefinished fiber cement siding products can be visually marred or damaged during storage. One damage mechanism is caused as a result of the heavy boards being stacked against each other. In some cases the weight against the bottom boards can exceed about 6 to 10 kg/cm2. The great weight can cause damage to the finish. In particular, the peaks of the embossed surface can be crushed, and the flattened peak can appear as a glossy spot.